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[209.85.220.65]) by mx.google.com with SMTPS id n4sor7215920qke.58.2019.06.17.07.04.32 for (Google Transport Security); Mon, 17 Jun 2019 07:04:32 -0700 (PDT) Received-SPF: pass (google.com: domain of arndbergmann@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; spf=pass (google.com: domain of arndbergmann@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=arndbergmann@gmail.com X-Google-Smtp-Source: APXvYqxfILWhAdKXQ4OWbwL16dTg8+0rppOl294W+m7hdTdNP3jcvSOtAIQCjQ3rZPM0axb4x4PZsoZRGkPIyUFm8U8= X-Received: by 2002:ae9:e608:: with SMTP id z8mr80292298qkf.182.1560780272294; Mon, 17 Jun 2019 07:04:32 -0700 (PDT) MIME-Version: 1.0 References: <20190617121427.77565-1-arnd@arndb.de> <457d8e5e453a18faf358bc1360a19003@suse.de> In-Reply-To: <457d8e5e453a18faf358bc1360a19003@suse.de> From: Arnd Bergmann Date: Mon, 17 Jun 2019 16:04:14 +0200 Message-ID: Subject: Re: [BUG]: mm/vmalloc: uninitialized variable access in pcpu_get_vm_areas To: Roman Penyaev Cc: "Uladzislau Rezki (Sony)" , Roman Gushchin , Michal Hocko , Matthew Wilcox , Thomas Garnier , Oleksiy Avramchenko , Steven Rostedt , Joel Fernandes , Thomas Gleixner , Ingo Molnar , Tejun Heo , Andrew Morton , Linus Torvalds , Stephen Rothwell , Rick Edgecombe , Andrey Ryabinin , Mike Rapoport , Linux-MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jun 17, 2019 at 3:49 PM Roman Penyaev wrote: > > augment_tree_propagate_from(va); > > > > - if (type == NE_FIT_TYPE) > > - insert_vmap_area_augment(lva, &va->rb_node, > > - &free_vmap_area_root, &free_vmap_area_list); > > - } > > - > > return 0; > > } > > > Hi Arnd, > > Seems the proper fix is just setting lva to NULL. The only place > where lva is allocated and then used is when type == NE_FIT_TYPE, > so according to my shallow understanding of the code everything > should be fine. I don't see how NULL could work here. insert_vmap_area_augment() passes the va pointer into find_va_links() and link_va(), both of which dereference the pointer, see static void insert_vmap_area_augment(struct vmap_area *va, struct rb_node *from, struct rb_root *root, struct list_head *head) { struct rb_node **link; struct rb_node *parent; if (from) link = find_va_links(va, NULL, from, &parent); else link = find_va_links(va, root, NULL, &parent); link_va(va, root, parent, link, head); augment_tree_propagate_from(va); } static __always_inline struct rb_node ** find_va_links(struct vmap_area *va, struct rb_root *root, struct rb_node *from, struct rb_node **parent) { ... if (va->va_start < tmp_va->va_end && va->va_end <= tmp_va->va_start) ... } static __always_inline void link_va(struct vmap_area *va, struct rb_root *root, struct rb_node *parent, struct rb_node **link, struct list_head *head) { ... rb_link_node(&va->rb_node, parent, link); ... } Arnd